Optical-read digital recording discs, including compact discs (CDs), digital versatile discs (DVDs), CD-ROMs, recordable CDs (CD-Rs), re-writable CDs (CD-RWs), game discs, and the like, are widely used to store different types of information. Such optical discs may be formatted for use with audio, video, game, or computer equipment that reads the data recorded on the discs. The technology associated with optical discs and digital playback equipment is well known to those skilled in the art. Basically, digital information is encoded and arranged in spiral data tracks within the disc beneath an optically transparent protective layer, or surface, of plastic. A laser beam reads the digital information during playback, and the information is then processed and presented to the user in the form of sound, visual images, or computer data.
The optically transparent protective surface forms the bulk of the thickness and weight of the disc. Generally, the protective surface protects the data layer from damage on the play side. In addition, the protective surface acts as a transparent substrate to support the data layer of the disc. Damage or surface imperfections located on the transparent protective surface can interfere with the laser beam before it reaches the data layer. Although modern playback devices include error correction techniques, this interference can prevent the player from reading the data correctly, or at all, even though the data layer itself is undamaged.
In recent years, the disc reclamation industry has prospered due to the widespread use and longevity of digital recording discs. However, many used discs cannot be resold because imperfections in the protective surface render them unplayable or visually unappealing. Consequently, to improve disc playability and visual appeal for resale, various methods for reconditioning the protective surface of an optical disc have been developed. The desire to improve disc playability and visual appeal is not limited to the reclamation industry. Many individuals desire to have the capability to recondition their discs at home.
A reconditioning apparatus that has substantial disc throughput, while effectively reconditioning optical discs, is fundamental to economic success in the commercial/industrial market. However, throughput may be less of a concern in the consumer market since the quantity of discs to be reconditioned by a consumer is likely to be much lower than that for the commercial market. As such, a reconditioning apparatus that is both affordable and effective at reconditioning optical discs is crucial to success in the consumer market.
It should be noted that in a reconditioning device, buffing speed should be balanced with heat removal. That is, the faster the relative speed between the buffing element and the optical disc, the faster the reconditioning. However, if the relative speed is inadequately controlled, i.e., the relative speed is too great, cooling liquid and polishing compound can be simply flung off of the optical disc. This leads to waste of the cooling liquid and/or polishing compound, as well as ineffective heat absorption and buffing.
Some machines use multiple motors or complicated transmission systems to drive both the buffing element and the optical disc in order to control the speed of the buffing element and the optical disc. Such devices are undesirably costly and have a higher probability of component failure due to the complexity of the equipment.
The pressure between the buffing element and the optical disc also affects the effectiveness of the reconditioning process. If the pressure is too great, too much material may be removed, which can damage the underlying data track and/or cause excessive heat build up. Conversely, if the pressure is too low, reconditioning time becomes undesirably long and less cost effective, especially in the commercial market. Yet another problem associated with pressure is the effect of uneven pressure between the contact surface of the buffing element and the protective surface of the optical disc. This uneven pressure can result in non-uniform reconditioning of the protective surface. This non-uniform reconditioning may cause laser beam focus problems, vibrations, and signal distortion during playback.
In order to control the pressure between the buffing element and the protective surface of the optical disc, many reconditioning devices employ complex and costly mechanisms that provide motion in multiple planes. By way of example, buffing elements may be rotated into position in one plane, then raised or lowered into position against the optical disc. Yet others use a flat, planar buffing surface that must be precisely aligned with the planar optical disc. Again, such devices are undesirably costly and have a higher probability of component failure due the complexity of the equipment.
It is known that optical discs can be effectively reconditioned by employing several sequential, successively finer, buffing stages. Conventional reconditioning devices require replacement of the buffing elements to progress from coarse to finer buffing stages, and/or complex machinery to return (i.e., raise or lower) the buffing elements into position against the optical disc between each of the buffing stages. Unfortunately, while this method may effectively repair the protective coating of a single digital disc, it is so time consuming that it is impractical for repairing a large number of discs. Furthermore, the complex machinery is too costly for the consumer market. Moreover, debris from the coarse buffing stage can contaminate the protective surface of the optical disc when performing the fine buffing, thus compromising the effectiveness of the finer buffing stages.
Accordingly, what is needed is a buffing head for a reconditioning apparatus that effectively and time-efficiently reconditions optical discs. There is also a need for a basic buffing element that is expandable between consumer, commercial, and industrial reconditioning apparatuses. That is, a buffing head, utilizing the buffing element, should be configurable for use in an affordable reconditioning apparatus for consumer applications. In addition, a buffing head, utilizing the buffing element should be configurable for high throughput reconditioning apparatuses for commercial/industrial applications.